Except that "moshimoshi" can also be used in person, while "konnichiwa" is never used when answering the phone.
And that "konnichiwa" is a greeting, while "moshimoshi" is not.
Also Konnichiwa as a greeting in person or before starting a phone conversation is used pretty much exclusively during the day (in writing it's always OK) and moshimoshi is used all the time to answer the phone. Moshimoshi not on the phone is often like "excuse me...hey are you still here ???" when the other person looks like they are more lost in their thoughts than yours.